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Description: A group isomorphism maps the zero of one group (and only the zero) to the zero of the other group. (Contributed by AV, 24-Oct-2019) (Revised by Thierry Arnoux, 23-May-2023)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | gim0to0.a | ||
| gim0to0.b | |||
| gim0to0.n | |||
| gim0to0.0 | |||
| Assertion | gim0to0 |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | gim0to0.a | ||
| 2 | gim0to0.b | ||
| 3 | gim0to0.n | ||
| 4 | gim0to0.0 | ||
| 5 | gimghm | ||
| 6 | 1 2 | gimf1o | |
| 7 | f1of1 | ||
| 8 | 6 7 | syl | |
| 9 | 5 8 | jca | |
| 10 | 9 | anim1i | |
| 11 | df-3an | ||
| 12 | 10 11 | sylibr | |
| 13 | 1 2 4 3 | f1ghm0to0 | |
| 14 | 12 13 | syl |